Ishii Daisuke, Yamasaki Hiroshi, Uozumi Ryosuke, Hirose Euichi
Department of Life Science and Applied Chemistry , Graduate School of Engineering , Nagoya Institute of Technology, Nagoya, Aichi 466-8555 , Japan.
Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan; Museum für Naturkunde Berlin, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, 10115 Berlin, Germany.
R Soc Open Sci. 2016 Oct 19;3(10):160512. doi: 10.1098/rsos.160512. eCollection 2016 Oct.
The body surface of aquatic invertebrates is generally thought to be hydrophilic to prevent the attachment of air bubbles. In contrast, some interstitial invertebrates, such as kinorhynchs and some crustaceans, have a hydrophobic body surface: they are often trapped at the water surface when the sediment in which they reside is mixed with air and water. Here, we directly measured the wettability of the body surface of the kinorhynch , using a microscopic contact angle meter. The intact body surface of live specimens was not hydrophobic, but the anterior part was less hydrophilic. Furthermore, washing with seawater significantly decreased the wettability of the body surface, but a hydrophilic surface was recovered after a 1 h incubation in seawater. We believe that the hydrophobic cuticle of the kinorhynch has a hydrophilic coat that is readily exfoliated by disturbance. Ultrastructural observations supported the presence of a mucus-like coating on the cuticle. Regulation of wettability is crucial to survival in shallow, fluctuating habitats for microscopic organisms and may also contribute to expansion of the dispersal range of these animals.
一般认为，水生无脊椎动物的体表具有亲水性，以防止气泡附着。相比之下，一些间隙性无脊椎动物，如动吻动物和一些甲壳类动物，体表具有疏水性：当它们所栖息的沉积物与空气和水混合时，它们常常被困在水面。在此，我们使用显微镜接触角测量仪直接测量了动吻动物体表的润湿性。活体标本完整的体表并非疏水，但前部的亲水性较差。此外，用海水冲洗会显著降低体表的润湿性，但在海水中孵育1小时后，亲水性表面得以恢复。我们认为，动吻动物的疏水角质层有一层亲水性涂层，该涂层很容易因扰动而脱落。超微结构观察结果支持角质层上存在类似黏液的涂层。润湿性的调节对于微小生物在浅水环境波动的栖息地中生存至关重要，也可能有助于扩大这些动物的扩散范围。
